Justin Gillis of The Times has summarized new research pointing to rising odds of costly coastal flooding coming from greenhouse heating of the planet. The nonprofit group Climate Central, which pursues a novel mix of original research and climate communication, is behind the new work, which is being published in the journal Environmental Research Letters. The group has produced a batch of maps and other resources building on the work.

It would’ve been better if the timing had been reversed, given the signs that many of the science findings of the extremes report, from the Intergovernmental Panel on Climate Change, are largely not reflected in the statements from the leaders in Dhaka.

Richard Black, the indispensable climate and environment reporter for the BBC (I urge you to follow him on Twitter @BBCrblack), has nicely summarized the disconnect in a piece describing the draft summary of the report on extreme meteorological events and relating it to claims of greenhouse-driven damages in poor places.

As has been the case for years, climate science points to measurably rising impacts from human-driven global warming later this century. And those impacts will be divided unevenly between the world’s poor, vulnerable countries and rich ones that are shielded from big impacts by wealth and are most responsible for building the global greenhouse blanket so far. (That “climate divide” was explored in twopieces in The Times in 2007.)

But the same research concludes that it’s difficult to link human-driven warming to losses in recent mega-disasters. Deeply confounding factors get in the way — particularly the huge growth in exposure to climate threats through population growth and settlement patterns in vulnerable places and the substantial natural variability in the frequency and intensity of rare extreme events.

Black starts by describing the three categories of climate and coastal impacts projected to intensify as greenhouse gases accumulate in the atmosphere: Read more…

Joshua K. Willis of NASA’s Jet Propulsion Laboratory is deeply involved in efforts to clarify oceanic ups and downs using space-based and deep-diving instruments. I frequently reach out to him when people tussle over the data and analysis pointing to rising seas in a human-heated world.

This arena remains dogged by durable uncertainty on time scales relevant to policy debates even as the long-term picture of centuries of rising seas is clear. One persistent issue is the dynamics of ice sheets. Another is persistent questions about how much heat the seas absorb. Not long ago I caught Willis for a brief Skype interview that explores some important recent studies and assertions: Read more…

New research on the dynamics of Greenland’s ice sheets complicates efforts to forecast sea level rise in this century, as the Green Blog reports. Expanding fields of crevasses appear to be limiting the flow of water to the base of the ice through tube-like moulins. That flow has been thought to ease the seaward movement of the ice over bedrock. But the crevasses also warm the ice as liquid water descends deep inside the frozen mass, with that process also potentially speeding its flow. This diagram shows the two types of plumbing:

I’ve queried a batch of researchers focused on ice sheets and sea level on these findings, and asked them how their views of sea level changes in a warming world have evolved since the 2007 report from the Intergovernmental Panel on Climate Change. I’ll be posting their thoughts soon.

Unfortunately, the tough scientific work to clarify ice and sea trends and dynamics has largely been obscured online by coverage focused on an error on Greenland ice loss that many polar scientists say made it into the new edition of the Times Comprehensive Atlas of the World (that’s the British Times, just to be clear). Of even greater concern were unsubstantiated assertions made by the atlas’s publisher, HarperCollins (which, while defending its atlas, has since apologized for the news release).

The publisher’s overstatements created ample fodder for critics of warnings about human-driven climate change and, fortunately, were also quickly pointed out by two of the leading scientific teams tracking polar change, the Scott Polar Research Institute in Britain and the National Snow and Ice Data Center in the United States.

There’s some emerging clarity, from independent lines of inquiry, about how much seas could rise in this century — with many researchers centering on a yard or so. Keep in mind that clarity doesn’t necessarily amount to a big shift in thinking. A yard by 2100 was seen as a probable outcome as long ago as 1992, when I wrote my first book on global warming.

The work cited by Gillis (along with other new research) indicates that a greater rise is plausible, should ice sheets in Antarctica and Greenland erode at their maximum possible pace, but there’s been little success at narrowing the probability of such a worst-case meltdown.

The reactions of several Dot Earth readers who’ve noted the piece, either admiringly or critically, appear to support the hypothesis that powerful cultural filters modulate how humans receive and interpret information. Here’s a portion of one comment, from the anonymous and cantankerous “Sere,” along with a link to the rest, followed by my reply: Read more…

Aug. 9, 8:30 a.m. | Updated An enormous iceberg, about four times the size of Manhattan, broke away from Greenland’s Petermann Glacier on Aug. 5.

Greenland has for years been shedding ice faster than the rate at which accumulating snow adds to the overall bulk of its ice sheet. The calving of an enormous ice “island” from the Petermann Glacier several days ago created a photogenic “moment” in a long-term process.

Petermann is a sleeping giant that is slowly awakening. Removing flow resistance leads to flow acceleration…. The coincidence of this area loss and a 30 square kilometer loss in 2008 with abnormal warmth this year, the setting of increasing sea surface temperatures and sea ice decline are all part of a climate warming pattern.

Questions about the eventual contribution to rising sea levels from Greenland’s eroding ice mass (and the West Antarctic Ice Sheet down south) remain hard to answer. I’ve put out a query to a batch of glaciologists for more thoughts and will update this post when they reply.

Aug. 9, 8:30 a.m. | Update Andreas Muenchow of the University of Delaware is much more cautious than Ohio State’s Jason Box about attributing the ice breakup to recent warming. He submitted a comment below that I’m highlighting here:

Air temperatures have very little to do with this breakup because this glacier is losing more than 80% of its ice by melting from the ocean below this floating glacier. The newly broken off piece, as massive as it is, contributes less than 10% of the ice lost over 50 years. If one wants to make the connection to global warming for this glacier, one will need to proof that ocean temperatures under the ice have increased. And from measuring those for a day in 2003 and a day in 2006 and a day in 2007 and a day in 2009, we are barely able to provide a first description that we submitted for peer review a few weeks ago, e.g., //muenchow.cms.udel.edu… … We are not even sure what the sill depth for this fjord is, e.g., the deepest part that connects Petermann Fjord with the rest of the ocean, within better than 100 meters. In much of the Arctic, temperature in the ocean increases with depth to about 300-500 meters which is the range of the likely sill depth. There is plenty of heat inside the fjord already to melt it from below (see linked manuscript), so an interesting question to ask (again, this may have nothing to do with climate change), why is the floating ice shelf there in the first place? Boundary layer physics, turbulence, tides, and glacier dynamics may all relate and may all be more fruitful ways in trying to understand what is happening than just to wave the hand and tick this off as another sign of global warming.

Global warming and climate change are very real and challenging problems, but it is foolish to assign every “visible” event to that catch-all phrase. It cheapens and discredits those findings where global warming is a real and immediate cause for observable phenomena. Details matter, in science as well as in policy.

I couldn’t agree more. It was important to note the development, as I did, but also to be careful about the lure of the “front-page thought.”

While American energy and climate policy remain paralyzed, physics isn’t standing still. And the science pointing to big, long-lasting consequences for the world from the buildup of greenhouse gases continues to accumulate.

Particularly consequential is the impact on ice sheets and, in the end, sea levels, much of which is already programmed into the system because of the heat banked in the oceans and the long lifetime of the most important human-generated greenhouse gas, carbon dioxide. For some insights on the need to adapt to this reality, even as policies on cutting emissions are crafted, read or listen to an interview conducted by Tom Yulsman, an old friend and journalism professor at the University of Colorado, with Jim White, a climate specialist there who just returned from Greenland.

The excerpt below follows a discussion of evidence that warming is likely to replicate conditions that persisted for millenniums during the last warm interval between ice ages, the Eemian, centered around 125,000 years ago. That period, warmer than the current warm stretch (at least for the moment), had sea levels around 10 to 15 feet higher than they are now. Read more…

If you have a dark sense of humor and need a chuckle to deal with such news, particularly in light of the ongoing stasis over international and United States policy on climate and energy, have a look at Marc Roberts’s latest cartoon posting, which is from his archives but all too relevant. An intergalactic environmental health and safety team comes to Earth and explains to a passing human: “We’ve been monitoring your carbon dioxide emissions and, quite frankly, we’re appalled.”

Jonathan Bamber of the Bristol Glaciology Center in England has led a new analysis of just how much the loss of West Antarctica’s ice could raise sea levels if the ice sheet fully disintegrated. He and his co-authors conclude in the current issue of Science that the maximum rise in seas, not including what could come from Greenland, of course, would be about 10 feet, half of the 20 feet or so that has been the rough projection for several decades. My news story on the study includes cautionary comments from some other Antarctic specialists who warn that the long-term rise in seas is less relevant than what could happen in the next 100 years. The new research was not aimed at answering the near-term question. (Here’s more on the long-term melt risk.)

Over all, there is clearly still a consensus that the prime question, how fast and far seas could rise in the next 100 years, remains laden with uncertainty. Still, there appears to be growing conviction among ice experts that a few more years of work really could clarify what’s possible, or not, on time scales relevant to today’s children and their children. Here’s a video showing one possible outcome for Antarctic ice, created by another research team whose work I covered here recently:

Paul BlanchonCoral fossils in canal walls at a Mexican resort show evidence of a rapid increase in sea level 121,000 years ago, researchers say. Other experts on corals and climate are not convinced.

For the last several days, I’ve been learning a lot about what old coral formations, which reflect the height of seas at different times in the past, might say about future sea levels in a warming world.

Paul Blanchon, who studies patterns of past coral growth for hints of environmental conditions, led a new study of remarkable fossil coral reefs on the Yucatan peninsula near Cancún, Mexico. The reef remains were exposed in canal walls and other excavations at the rather remarkable-looking Xcaret water park and resort. (Have any readers been there?)

He asserts that the corals there are a “smoking gun” proving that a drastic jump in sea levels, of up to 10 feet in 50 years, occurred in a climate warmer than today’s. I have written a news article on the coral study. If Dr. Blanchon’s conclusion, published in the April 16 issue of Nature, holds up, it delivers a momentous warning that sea changes driven by the buildup of greenhouse gases need not be smooth and could be utterly devastating. For the moment that appears to be a big “if,” given the concerns of other scientists familiar with coral clues to past conditions of the ocean and climate.

As time allows, I’ll add some thoughts from climate and coral experts beyond what is provided in my article.

About

By 2050 or so, the human population is expected to pass nine billion. Those billions will be seeking food, water and other resources on a planet where humans are already shaping climate and the web of life. Dot Earth was created by Andrew Revkin in October 2007 -- in part with support from a John Simon Guggenheim Fellowship -- to explore ways to balance human needs and the planet's limits.